1. Field of the Invention
The present invention relates to an ultrasonic endoscope in which an endoscopic observation section that has an observation visual field ahead of a distal hard part of an insertion portion and an electronic scanning type ultrasonic transducer that has a circumferential or circularly arcuate ultrasonic scan surface perpendicular to an axial line of the distal hard part are attached to the distal hard part.
2. Description of the Related Art
An ultrasonic endoscope has a structure in which an endoscopic observation means and an ultrasonic transducer are attached to a distal hard part of an insertion portion that is inserted into, for example, a body cavity. As a scanning manner by this ultrasonic transducer, a so-called electronic scanning type ultrasonic transducer in which a large number of ultrasonic vibrators are arranged in a predetermined direction, and are sequentially driven is widely used in the related art. For example, JP-A-2001-314403 describes a direct-view endoscope in which an area in front of the distal hard part of the insertion portion is observed as an observation visual field in the endoscopic observation means, and an ultrasonic scan surface by the ultrasonic transducer is made to be radial, i.e., circumferential or arcuate within a predetermined angular range.
The ultrasonic endoscope disclosed by this JP-A-2001-314403 is inserted into, for example, body cavity tubes, i.e., upper alimentary canals, such as the esophagus and the duodenum, or lower alimentary canals, such as the large intestine, so that a forward area in the insertion direction is observed by the endoscopic observation means. As a result, if a region of interest, such as diseased parts, is detected, the ultrasonic transducer is positioned to face this region of interest, whereby information on body tissues of the region can be obtained.
Herein, wires are respectively connected to ultrasonic vibrators, which constitute the ultrasonic transducer, in the ultrasonic transducer. However, it is difficult to connect these wires directly to the ultrasonic vibrators. Therefore, in general, flexible boards are connected to the ultrasonic vibrators arranged in the circumferential direction, and terminal parts the number of which corresponds to the number of ultrasonic vibrators are formed on the flexible boards, and then the wires are connected to the terminal parts by, for example, a soldering means.
As described above, a large number of ultrasonic vibrators are arranged in the circumferential direction if the ultrasonic scan surface is in the radial direction. However, to heighten the resolution of an ultrasonic tomographic image, the number of ultrasonic vibrators is increased. From the viewpoint of making the diameter of the insertion portion smaller, the area of the flexible board cannot be widened. Therefore, in the flexible board, the distance between the terminals becomes close even if the wire-connecting terminals are zigzag arranged as a possible design. As a result, it becomes difficult to connect the wires to the terminals, and there is a possibility that connection strength will be weakened. Additionally, there is a possibility that, for example, a short circuit is disadvantageously caused by allowing solder to overflow from the terminal part.